There is conventionally known a display device provided with a backlight device including a diffusion plate. FIGS. 12 and 13 are cross-sectional views showing the structure of a display device provided with, as a conventional example, a backlight device including a diffusion plate.
As shown in FIG. 12, a display device 101 is composed of a display panel 102, a bezel 103 covering a circumferential edge of the display panel 102, and a direct backlight device 110 disposed on the back side of the display panel 102.
The backlight device 110 includes a backlight frame 111, a reflection sheet 112, a plurality of light sources 113, and a diffusion plate 114 that diffuses light from the light sources 113.
The backlight frame 111 includes a back surface portion 111a as well as an upper surface portion 111b and a lower surface portion 111c that are fixed to the back surface portion 111a. Contact members 115 and 116 with which a light incidence surface 114a of the diffusion plate 114 comes into contact are fixed to the upper surface portion 111b and the lower surface portion 111c, respectively.
Furthermore, a support member 117 that is disposed below the diffusion plate 114 and has a support surface 117a for supporting the diffusion plate 114 is fixed to the lower surface portion 111c of the backlight frame 111. The support surface 117a of the support member 117 is formed so that, in a state where the display device 101 (diffusion plate 114) is placed vertically (state shown in FIG. 12), it comes into contact with the entire area of the lower surface of the diffusion plate 114.
Furthermore, the diffusion plate 114 is disposed so that, in the state where the display device 101 (diffusion plate 114) is placed vertically, it is parallel to the display panel 102 and extends in a vertical direction.
There is also conventionally known a display device provided with, similarly to the above-described display device 101, a backlight device including a support member disposed below a diffusion plate (see, for example, Patent Document 1).
Patent Document 1 described above discloses a liquid crystal display device including a color liquid crystal display panel (display panel), an outer frame (bezel) covering a circumferential edge of the color liquid crystal display panel, and a direct backlight device disposed on the back side of the color liquid crystal display panel.
The backlight device of this liquid crystal display device includes a backlight housing portion, a reflection sheet disposed inside the backlight housing portion, a reflection plate (support member) supporting the reflection sheet, a plurality of light-emitting diodes (light sources), a diffusion light guide plate and a diffusion plate that are disposed forward of the light-emitting diodes (on the side of the color liquid crystal display panel), and an optical sheet disposed forward of the diffusion plate (on the side of the color liquid crystal display panel).
The diffusion plate is disposed so that, in a state where the liquid crystal display device is placed vertically, it is parallel to the color liquid crystal display panel and extends in a vertical direction.
The reflection plate is disposed below the diffusion light guide plate and the diffusion plate in the state where the liquid crystal display device is placed vertically and has two support surfaces for supporting the diffusion light guide plate and the diffusion plate.
These two support surfaces are formed so that, in the state where the liquid crystal display device is placed vertically, they come into contact with the entire area of the lower surface of the diffusion light guide plate and the entire area of the lower surface of the diffusion plate, respectively.
Furthermore, an inclined surface is formed between the two support surfaces of the reflection plate. This inclined surface is provided for the purpose of controlling a reflection direction of light.    Patent Document 1: JP-A-2006-301210